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Seeing Chinook as Indicators

This article was written by Alex Steffen in March 2008. We're republishing it here as part of our month-long editorial retrospective.


To get a sense of how complex and tangled the task is of managing the planet, consider Chinook salmon.

The Sacramento River fall Chinook salmon run, which had been recovering in recent years, has suddenly collapsed, and no one seems to know why:

The almost complete collapse of the richest and most dependable source of Chinook salmon south of Alaska left gloomy fisheries experts struggling for reliable explanations — and coming up dry.

...Fishermen think the Sacramento River was mismanaged in 2005, when this year’s fish first migrated downriver. Perhaps, they say, federal and state water managers drained too much water or drained at the wrong time to serve the state’s powerful agricultural interests and cities in arid Southern California. The fishermen think the fish were left susceptible to disease, or to predators, or to being sucked into diversion pumps and left to die in irrigation canals.

But federal and state fishery managers and biologists point to the highly unusual ocean conditions in 2005, which may have left the fingerling salmon with little or none of the rich nourishment provided by the normal upwelling currents near the shore.

The life cycle of these fall run Chinook salmon takes them from their birth and early weeks in cold river waters through a downstream migration that deposits them in the San Francisco Bay when they are a few inches long, and then as their bodies adapt to saltwater through a migration out into the ocean, where they live until they return to spawn, usually three years later.

What wiped out the run? Climate change? Water diversions? Something we don't understand? The answer may well be all three, which illustrates the difficulty of trying to manage a complex natural system through highly political processes (which in the real world is essentially the only way they ever are managed).

Why care so much about the salmon? Well, fall Chinook are a $150 million fishery, first of all. That's a lot of fish missing from a lot of tables, and a lot of fishermen looking at hard times.

But there's another reason we should care: river and mountain ecosystems throughout the North Pacific depend on salmon to remain healthy. Here's how Ed Hunt explains it:

Pacific salmon do a strange thing. After they spawn, they die. ...After spawning, they leave their nutrient-rich carcasses behind. Many of the microscopic creatures that nibble on the carcasses eventually become prey for the next generation of fish. And so the parents nourish the young.

But salmon provide more than an indirect food source for baby salmon. At least 137 different species — from grizzly bears to gray wolves — depend on salmon for part of their diet. Even trees and plants benefit from the nutrients brought back by salmon from the seas.

Indeed, salmon used to transport so many marine nutrients to terrestrial ecosystems that environmental historian Richard White compared them to a conveyor belt. As Richard Manning explains:

Salmon are born, leave the stream as a pencil-sized fish, spend a few years fattening on ocean's bounty, then return with a gift to the natal stream, as much as 60 pounds of body mass made of not just carbon, but of the other nutrients the entire system needs. They import nutrients to landlocked life. This is the measure of the power of salmon.

Scientists now estimate that the Columbia River system once gained about 400 million pounds of nutrients from each year's salmon runs, before the dams broke the cycle. ... Samples of salmonberry bushes growing streamside reveal as much as 18 percent of their nutrients are ocean-derived, making it one of the more aptly named plants around. The same is true of trees. Plants are fed when carcasses decay and fertilize the soil, or when the dead salmon enter the food chain and eventually return to the soil as droppings. The faunal section of the chain contains at least 20 vertebrate species, including, of course, bears, but also surprisingly, deer and elk, which during spawning season are known to feed directly on salmon carcasses.

The upshot is that when the wrong forces combine -- when upwelling fails, ocean dead zones spread, streamside habitats are logged or developed and rivers are diverted to farmers' fields -- what is lost is not just a whole bunch of big fish, but the fundamental health of the ecosystems of an entire region.

If we're going to take our obligations as planetary managers seriously, we need to start being able to see through two lenses simultaneously -- a human lens and an systems lens -- and bring them into focus together. Despite decades of really smart, committed people trying to do that in Western North America, our vision's still blurry.

What might clear it up?

(If you want to learn more about salmon, by the way, I highly recommend browsing around over on the excellent Salmon Nation website.)

Creative Commons photo credit

Seeing Through Salmon is part of our month long retrospective leading up to our anniversary on October 1. For the next four weeks, we'll celebrate five years of solutions-based, forward-thinking and innovative journalism by publishing the best of the Worldchanging archives.

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